1. Field of the Invention
This invention relates to film transportation devices for cameras and more particularly to film transportation devices for cameras with means making it possible to superimpose two or more photographs or exposures.
2. Description of the Prior Art
It is known in the art to provide a wide variety of cameras which are made to permit intentional double and multiple exposures on the same frame of film by using an arrangement whereby the film rewind release member is latched in the rewinding position with the drive connection between the rapid-winding lever (or, in the case of the automatic camera, the motor) and the sprocket being cut off. With the rewind release member held in the rewinding position, when a winding operation of the camera is effected, the shutter mechanism only is allowed to operate. Responsive to termination of a certain winding operation, the rewind release member is released from the latching connection. For example, U.S. Pat. No. 4,089,483 (May 16, 1978) discloses a camera in which means is provided for hindering the rewind release button from returning, this hindering means being arranged upon termination of the winding operation to be pushed away by a cam which rotates in a certain direction when winding is being performed, so that the rewind release button returns to the initial position.
However, in such a conventional camera, because it uses the cam in taking the rewind release button out of the locking connection as the rotation of the cam stops when the shutter cocking operation is terminated, there arises a drawback in that in order to achieve an accurate superimposition of two or more exposures in the same frame of film, it is required that the sprocket and the rapid winding lever (or motor) not be brought into drive connection with each other until cocking of the shutter is completed. For this purpose, according to such prior art, the aforementioned cam must be arranged to release the rewind button from the locking connection at exactly the same time that the cocking operation is terminated. In actual practice, however, it is impossible to always establish such accurate synchronization. With such means, therefore, it often happens that when cocking the shutter to superimpose the next shot, the film is caused to advance though a short length, or that the aforementioned locking connection cannot release.
To improve the reliability of operation, each part must be manufactured within a very severe tolerance for precision accuracy, thereby creating an additional disadvantage from an economical standpoint.